System and method for providing inductive power at multiple power levels

ABSTRACT

A system and method for inductively providing electrical power at a plurality of power levels to electrical devices. The system may include an inductive power outlet unit conductively coupled to a power supply and an inductive power receiver unit associated with the electrical device. The inductive power outlet unit includes a driver device operable to generate power at a plurality of power levels and electrical power is transferred to the electrical device at a power level selected from the plurality of power levels, in accordance with electrical power requirements of the electrical device. The power receiver may be operable in a plurality of modes having a secondary inductor configured to operate selectively with a plurality of inductance values.

CROSS REFERENCE TO RELATED APPLICATION(S)

This patent application is a continuation of co-pending U.S. patentapplication Ser. No. 17/498,569, filed Oct. 11, 2021, which is acontinuation of co-pending U.S. patent application Ser. No. 17/482,106,filed Sep. 22, 2021, which is a continuation of co-pending U.S. patentapplication Ser. No. 16/989,226, filed Aug. 10, 2020 (now U.S. Pat. No.11,183,888, issued Nov. 23, 2021), which is a continuation of U.S.patent application Ser. No. 14/412,843, filed Jan. 5, 2015 (now U.S.Pat. No. 10,770,927, issued Sep. 8, 2020), which in turn is a NationalStage filing under 35 U.S.C. § 371 of PCT Patent Application No.PCT/IL2013/050576, filed Jul. 4, 2013, which is based upon and claimspriority to U.S. Provisional Patent Application Ser. No. 61/668,250,filed Jul. 5, 2012 and to U.S. Provisional Patent Application Ser. No.61/669,394, filed Jul. 9, 2012, the disclosures of each of which areincorporated herein by reference.

FIELD OF INVENTION

The present disclosure relates to a system and method for inductivelyproviding AC electrical power to an electrical device at non-resonantfrequencies of an inductive power transfer system. The disclosurefurther relates to multi-mode inductive power receivers operable inaccordance with a plurality of operating protocols.

BACKGROUND

Inductive power coupling allows energy to be transferred from a powersupply to an electric load without a wired connection therebetween. Anoscillating electric potential is applied across a primary inductor.This sets up an oscillating magnetic field in the vicinity of theprimary inductor. The oscillating magnetic field may induce a secondaryoscillating electrical potential in a secondary inductor placed close tothe primary inductor. In this way, electrical energy may be transmittedfrom the primary inductor to the secondary inductor by electromagneticinduction without a conductive connection between the inductors.

When electrical energy is transferred from a primary inductor to asecondary inductor, the inductors are said to be inductively coupled. Anelectric load wired in series with such a secondary inductor may drawenergy from the power source wired to the primary inductor when thesecondary inductor is inductively coupled thereto.

In order to control inductive power transfer between an inductive poweroutlet and an inductive power receiver various protocols have beensuggested to enable regulation of power level and the like. For example,one such protocol is described in the applicant's co-pending U.S. patentapplication Ser. No. 13/205,672 titled “Energy Efficient Inductive PowerTransmission System and Method,” now U.S. Pat. No. 8,981,598, which isincorporated herein by reference.

It is known in the art that inductive power transfer systems transfer ACelectrical power at the resonant frequency of the inductive powertransfer system. However, small fluctuations in the resonant frequencyduring power transmissions may result in substantive changes and lossesin the transferred electrical power. Fluctuations in the inductiveresonant frequency may be due to changing environmental conditions orvariations in alignment between primary inductive and secondaryinductive coils.

Further, efficient inductive power transfer is only practical where theinductive receiver uses the same protocol as the inductive power outlet.Inductive receivers are generally configured to work according to onlyone control protocol. However, because of the variety of protocolscurrently in use, not all inductive receivers are compatible with allinductive power outlets.

Thus, there is a need in the art for an inductive power transfer systemwith a higher tolerance to environmental fluctuations and variations ininductive coil alignment and to low voltages transmissions, as well as aneed in the art of an inductive power receiver operable to workaccording to multiple control protocols.

SUMMARY

The present disclosure provides a system and method for inductivelyproviding electrical power at a plurality of power levels to electricaldevices.

In the present disclosure, an inductive power transfer system provideselectrical power to an electrical device. The inductive power transfersystem includes, inter alia, an inductive power outlet unit conductivelycoupled to a power supply and an inductive power receiver unitassociated with the electrical device. The inductive power outlet unitincludes, inter alia, a primary inductor conductively coupled to thepower supply via a driver device. The power supply may supply a DCcurrent to the driver device. The driver device is configured to convertthe input DC voltage to an AC voltage. The frequency of the transferredAC voltage is determined by a toggling frequency, f_(T), of the driverdevice. The toggling frequency, f_(T), is optionally selected such thatthe AC voltage has a voltage transmission frequency, f, which may behigher or lower than the resonant frequency, f_(R), of the powerinductive system. Thus, deviations of the transmission frequency fromthe resonant frequency of the inductive power transfer system, do notresult in large variations in the transferred voltage. Optionally, inaccordance with a selected embodiment of the present disclosure, a rangeof toggle frequencies is selected, such that the transferred power hasan approximate “linear dependency” on the AC transmission frequency. TheAC electrical power is supplied to the electrical device, in accordancewith electrical power requirements of the electrical device.

The driver device may include a plurality of electronic switchesconfigured and operable to be selectively activated such that the driverdevice is operable to generate power at a plurality of power levels andelectrical power is transferred to the electrical device at a powerlevel selected from the plurality of power levels, in accordance withelectrical power requirements of the electrical device.

Variously, the driver device may include, inter alia, a power converter,which optionally includes, inter alia, four electronic switches, such asN-Type MOFSET devices and the corresponding control microprocessors ordrivers. Each pair of electronic switches may be controlled by a controlmicroprocessor. The electronic switches are conductively coupled to theDC power supply. The four switches constitute a full-bridge (H-bridge)power inverter for converting the DC voltage into the AC voltage. Thefull-bridge power converter includes a first half-bridge powerconverter, which includes a first pair of the electronic switches andits corresponding microprocessor and a second half-bridge powerconverter, which includes a second pair of electronic switches and acorresponding control microprocessor. An LC circuit conductively linksthe first half-bridge converter and the second half-bridge converter.

In accordance with a selected embodiment of the present disclosure, in afirst power mode, by operating the first half-bridge and the secondhalf-bridge, sequentially, a square-wave AC voltage, with a voltagerange of ±V volts, where V volts is the DC supply voltage, is generated.Accordingly, a voltage range of ±V volts may be generated over aresonant LC circuit. Additionally or alternatively, in a second powermode, by only operating a single bridge-member of the power converter, asquare-wave AC voltage, with a voltage range from 0 volts to V volts isgenerated.

Furthermore, by varying the DC voltage supply, the present disclosureprovides a versatile electrical power source for different electricaldevices, each electrical device having its particular varying electricalpower requirements. Additionally or alternatively, the duty cycle of thesquare wave may be adjusted to vary the amount of transmitted energy, asrequired.

It is appreciated that for electrical devices which require a DC voltagefor operation, an AC-DC rectification is included in the system.

There is provided in accordance with a selected embodiment of thepresent disclosure, an inductive power transfer system including atleast one inductive power outlet unit including at least one primaryinductor conductively coupled to a power supply via a driver device. Thedriver device is configured to provide an oscillating voltage across theat least one primary inductor, the at least one primary inductor formingan inductive couple with at least one secondary inductor associated withan electrical device, the at least one secondary inductor associatedwith an inductive power receiver. The AC voltage is inductivelytransferred to the inductive power receiver unit such that electricalpower at the plurality of power levels is transferred to the electricaldevice, in accordance with electrical power requirements of theelectrical device.

There is provided in accordance with another selected embodiment of thepresent disclosure, a method for inductively transferring electricalpower to an electrical device, including providing at least oneinductive power outlet unit including at least one primary inductor,providing a driver device conductively associated with a power supply,configuring the driver device to provide an AC voltage across the atleast one primary inductor, the at least one primary inductor forming aninductive couple with at least one secondary inductor associated with aninductive power receiver unit and configuring the power receiver unit toprovide an induced AC voltage to an electrical device conductivelycoupled with the power receiver unit, in accordance with electricalpower requirements of the electrical device.

Further in accordance with a selected embodiment of the presentdisclosure, the driver device includes a power inverter for converting aDC voltage generated by a DC power supply to the AC voltage. The powerconverter includes a first electronic switch being operable toselectively conductively couple an anode of the DC power supply to afirst terminal of the primary inductor, a second electronic switch beingoperable to selectively conductively couple a cathode of the DC powersupply to the first terminal of the primary inductor, a third electronicswitch being operable to selectively conductively couple the anode ofthe DC power supply to a second terminal of the primary inductor, and afourth electronic switch being operable to selectively conductivelycouple the cathode of the DC power supply to the second terminal of theprimary inductor. The power inverter is toggled between a firstoperational state and a second operational state, the AC voltage isgenerated across the primary inductor at least one power level of theplurality of power levels.

Still further in accordance with a selected embodiment of the presentdisclosure, at a first power mode of the driving AC voltage, the firstoperational state includes the first electronic switch being operable inan ON-state, the second electronic switch being operable in anOFF-state, the third electronic switch being operable in an OFF-state,and the fourth electronic switch being operable in an ON-state. Thesecond operational state includes the first electronic switch beingoperable in an OFF-state, the second electronic switch being operable inan ON-state, the third electronic switch being operable in an ON-state,and the fourth electronic switch being operable in an OFF-state.

Additionally in accordance with a selected embodiment of the presentdisclosure, at a second power mode of the AC voltage, the firstoperational state includes the first electronic switch being operable inan ON-state, the second electronic switch being operable in anOFF-state, the third electronic switch being operable in an OFF-state,and the fourth electronic switch being operable in an ON-state. Thesecond operational state includes the first electronic switch beingoperable in an OFF-state, the second electronic switch being operable inan ON-state, the third electronic switch being operable in an OFF-state,and the fourth electronic switch being operable in an ON-state.

Further in accordance with a selected embodiment of the presentdisclosure, the first power mode and the second power mode arecharacterized by a common range of toggle frequencies, voltages, dutycycle variations, or the like.

Still further in accordance with a selected embodiment of the presentdisclosure, the toggling frequencies include a frequency range in whichthe induced AC voltage varies approximately linearly with the togglefrequencies.

Additionally in accordance with a selected embodiment of the presentdisclosure, the driver device is configured to adjust the togglefrequencies in response to feedback signals.

The feedback signals include data pertaining to the electrical powerrequirements of the electrical device.

Further in accordance with a selected embodiment of the presentdisclosure, the toggling frequencies are selected in accordance with theelectrical power requirements of the electrical device.

Further in accordance with a selected embodiment of the presentdisclosure, the inductive power receiver unit further includes a powermonitor inductively coupled to the secondary inductor and configured tomonitor the electrical power transferred to the secondary inductor and afeedback signal generator conductively coupled to the power monitor andconfigured to adjust the toggling frequencies in accordance with themonitoring thereby ensuring that the inductive power transfer systemtransfers the electrical power to the electrical device in accordancewith the electrical power requirements,

Additionally in accordance with a selected embodiment of the presentdisclosure, the inductive power transfer system further including anAC-DC rectifier conductively coupling the power receiver unit and theelectrical device and configured to rectify the induced AC voltagethereby supplying a DC voltage to the electrical device, in accordancewith the electrical power requirements of the electrical device.

Optionally, the electrical device includes at least one of the followingelectrical devices: a mobile communications device, a navigation system,a computing device, a laptop computer, a net-book, a tablet computer, anelectronic reading device, a media player, or the like as well as anycombination thereof.

Further in accordance with a selected embodiment of the presentdisclosure, the electronic switch device is a MOFSET device.Additionally or alternatively, the electronic switch device may be abipolar transistor, such as a junction transistor or the like.

The present disclosure further provides for an inductive power receiveroperable in a plurality of modes such that it may be compatible withinductive power outlets operating with various protocols. The presentdisclosure addresses this need.

According to one aspect of the disclosure, an inductive power transfersystem is presented comprising at least one multi-mode inductive powerreceiver operable to receive power from at least one inductive poweroutlet, wherein the inductive power receiver is operable in a pluralityof modes, the multi-mode inductive power receiver comprising at leastone secondary inductor configured to operate selectively with aplurality of inductance values.

Optionally, the secondary inductor comprises a plurality of terminalsconfigured to connect to a reception circuit and wherein the inductancebetween a first pair of the terminals has a first value and theinductance between a second pair of the terminals has a second value.

Where appropriate, the secondary inductor comprises at least a commonterminal, a first mode terminal, and a second mode terminal wherein thefirst pair of terminals comprises the common terminal and the first modeterminal, and the second pair of terminals comprises the common terminaland the second mode terminal. For example, where appropriate, theinductance between the first pair of terminals is about 7.5microhenries, and the inductance between the second pair of terminals isabout 3.2 microhenries.

Optionally, the inductive power transfer system further comprises a modeselector operable to select at least one of a plurality of operatingprotocols. The mode selector may be operable to connect a receptioncircuit to the secondary inductor with at least one of the plurality ofinductances. Variously, the mode selector comprises at least one ACswitch operable to connect a reception circuit to a selected terminal ofthe secondary inductor. For example, the AC switch comprises a pair ofN-channel FETs having a common source signal, and a pair of P-channelFETs having a common gate signal and configured to connect the receptioncircuit to a selected terminal of the secondary inductor, wherein thecommon gate signal of the P-channel FETs is drawn from a charge pump viathe pair of N-channel FETs.

Where appropriate the mode selector may be in communication with afrequency detector operable to detect operating frequency of the primaryinductor. Accordingly, the mode selector may be operable to select afirst operating mode if the operating frequency is above a thresholdvalue, and to select a second operating mode if the operating frequencyis below the threshold value. Other decision mechanisms will occur tothose skilled in the art.

According to certain examples, the secondary inductor comprises a spiralof conducting material having an inner terminal at an inner end of thespiral, an outer terminal at an outer end of the spiral and anintermediate terminal conductively connected to the conducting materialof the spiral at an intermediate point between the inner end and theouter end. Optionally, the spiral of conducting material has an innerdiameter of about 20 millimeters and an outer diameter of about 33millimeters. The spiral may comprise 14 windings between the innerterminal and the outer terminal and 8 windings between the intermediateterminal and the outer terminal. Accordingly, the inductance at 100kilohertz and 1 volt between the inner terminal and the outer terminalmay be about 7.5 microhenries, and the inductance at 100 kilohertz and 1volt between the intermediate terminal and the outer terminal is about3.2 microhenries. Furthermore, the direct current resistance between theinner terminal and the outer terminal is about 298 milliohms, and thedirect current resistance between the intermediate terminal and theouter terminal is about 188 milliohms.

Another aspect of the disclosure is to teach a method for transferringpower inductively comprising inducing a voltage in a secondary inductor,detecting operating frequency of the induced voltage; if the operatingfrequency is above a threshold value, selecting a first operating mode,and if the operating frequency is below the threshold value, selecting asecond operating frequency. Optionally, the threshold value is 250kilohertz. Other data protocols between the transmitter and receiver assuitable requirements will occur to those skilled in the art.

It is noted that in order to implement the methods or systems of thedisclosure, various tasks may be performed or completed manually,automatically, or combinations thereof. Moreover, according to selectedinstrumentation and equipment of particular embodiments of the methodsor systems of the disclosure, some tasks may be implemented by hardware,software, firmware or combinations thereof using an operating system.For example, hardware may be implemented as a chip or a circuit such asan ASIC, integrated circuit, or the like. As software, selected tasksaccording to embodiments of the disclosure may be implemented as aplurality of software instructions being executed by a computing deviceusing any suitable operating system.

In various embodiments of the disclosure, one or more tasks as describedherein may be performed by a data processor, such as a computingplatform or distributed computing system for executing a plurality ofinstructions. Optionally, the data processor includes or accesses avolatile memory for storing instructions, data, or the like.Additionally or alternatively, the data processor may access anon-volatile storage, for example, a magnetic hard-disk, flash-drive,removable media, or the like, for storing instructions and/or data.Optionally, a network connection may additionally or alternatively beprovided. User interface devices may be provided such as visualdisplays, audio output devices, tactile outputs, and the like.Furthermore, as required user input devices may be provided such askeyboards, cameras, microphones, accelerometers, motion detectors, orpointing devices such as mice, roller balls, touch pads, touch sensitivescreens, or the like.

BRIEF DESCRIPTION OF THE DRAWING(S)

For a better understanding of the embodiments and to show how it may becarried into effect, reference will now be made, purely by way ofexample, to the accompanying drawings.

With specific reference now to the drawings in detail, it is stressedthat the particulars shown are by way of example and for purposes ofillustrative discussion of selected embodiments only, and are presentedin the cause of providing what is believed to be the most useful andreadily understood description of the principles and conceptual aspects.In this regard, no attempt is made to show structural details in moredetail than is necessary for a fundamental understanding; thedescription taken with the drawings making apparent to those skilled inthe art how the several selected embodiments may be put into practice.In the accompanying drawings:

FIG. 1 shows an inductive power transfer system for providing electricalpower to an electrical device, in accordance with a selected embodimentof the present disclosure;

FIG. 2 shows a variation in the transferred AC power as a function ofthe AC transmission frequency, f, in accordance with a selectedembodiment of the present disclosure;

FIG. 3 presents a typical circuit diagram of the inductive powertransfer system, in accordance with a selected embodiment of the presentdisclosure;

FIG. 4 shows a power converter of the driver device, in accordance witha selected embodiment of the present disclosure;

FIG. 5 shows an equivalent electronic circuit of the first half-bridgeconverter of the driver device, in accordance with a selected embodimentof the present disclosure;

FIGS. 6A and 6B present typical driver output voltages of the driverdevice operating in the first power mode and the second power mode,respectively, in accordance with a selected embodiment of the presentdisclosure;

FIG. 7 shows various operational power variations for the first andsecond power modes shown as a function of the transmission frequency, inaccordance with a selected embodiment of the present disclosure;

FIG. 8 shows variations of an operational power at different powermodes, as a function of the transmission frequency, in accordance with aselected embodiment of the present disclosure;

FIG. 9 presents further features of the inductive power transfer system,including a power monitor and feedback signal generator, in accordancewith a selected embodiment of the present disclosure;

FIG. 10 presents a flow chart showing selected steps in a method forinductively transferring the electrical power to the electrical device,in accordance with a selected embodiment of the present disclosure;

FIG. 11 is a block diagram showing selected elements of an inductivepower transfer system including a multi-mode inductive power receiveroperable to receive power in a plurality of modes;

FIGS. 12A and 12B schematically represent a multi-inductance secondaryinductor configured to operate selectively with more than one inductancevalue;

FIG. 13 is another block diagram showing selected elements of aparticular multi-mode secondary receiver incorporating themulti-inductance secondary inductor of FIGS. 12A and 12B;

FIGS. 14A-G show various sections of a possible reception circuit for amulti-mode inductive power receiver; and

FIG. 15 is a flowchart representing various actions of a method forselecting an operational mode of a multi-mode inductive power receiver.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Reference is now made to FIG. 1 , which shows an inductive powertransfer system 10 for providing electrical power 12 to an electricaldevice 14, in accordance with a selected embodiment of the presentdisclosure. The inductive power transfer system 10 includes, inter alia,an inductive power outlet unit 16 conductively coupled to a power supply18, for example, a DC power supply and an inductive power receiver unit20 conductively associated with the electrical device 14.

The inductive power outlet unit 16 includes, inter alia, a primaryinductor 22 conductively associated with the power supply 18 via adriver device 24. The DC power supply 18 supplies a DC current 26 to thedriver device 24. The driver device 24 is coupled to the primaryinductor 22 and is configured to generate an AC voltage 27, byconverting the input DC voltage 26 to an AC voltage 27 at a plurality ofpower levels, as described below. The AC voltage 27 is applied acrossthe primary inductor 22, and an AC voltage 28 is inductively transferredto the secondary inductor 30 via an inductive communications channel 15.The frequency of the AC voltage 28 is determined by a togglingfrequency, f_(T), of the driver device 24, as described below. Thetoggling frequency, f_(T), is selected such that the AC voltage 28 has avoltage transmission frequency f which is significantly different fromthe resonant frequency f_(R) of the power inductive system 10.

The inductive power receiver unit 20, which is conductively associatedwith the electric device 14, includes, inter alia, a secondary inductor30 inductively coupled 32 to the primary inductor 22 via the inductivecommunications channel 15. An AC voltage 34 is inductively transferredto the inductive power receiver unit 20 such that the electrical power12, at the plurality of power levels, is supplied to the electricaldevice 14 via an electrical device input channel 35, in accordance withelectrical power requirements of the electrical device 14.

In accordance with the selected embodiment of the present disclosure,the AC voltage 28 has a voltage transmission frequency, f, which ishigher than the resonant frequency f_(R) of the inductive power outletunit 16, as described below.

It is appreciated that in alternative embodiments of the presentdisclosure, the voltage transmission frequency, f, may be selected infrequency ranges which are less than f_(R).

Optionally, the electrical device 14 includes, inter alia, devices, suchas a mobile communications device, a navigation system, a computingdevice, a laptop computer, a net-book, a tablet computer, an electronicreading device, a media player, or the like as well as any combinationthereof.

Reference is now made to FIG. 2 , which shows a variation 31 in thetransferred AC power as a function of the AC transmission frequency, f,in accordance with a selected embodiment of the present disclosure. Itis appreciated that the AC transmission frequency is substantially thesame frequency as the toggling frequency of the driver device 24. FIG. 2shows that the maximum power transfer 32 is achieved at the resonantfrequency, f_(R), of the inductive power transfer system 10, namely, theresonant frequency of the primary inductor 22 and the secondary inductor30. However, due to power fluctuations, during power transmission, forexample, due to changing environmental conditions and/or variations inalignment between the primary and secondary inductors, small variationsin the transfer frequency results in large variations in the transferredpower 34. Therefore, it is preferable to operate the inductive powertransfer system 10 at transmission frequencies other than the resonantfrequency, f_(R).

In accordance with a selected embodiment of the current disclosure, aselected power transfer is in the power region in which thecorresponding transfer frequency is in a non-resonance frequency region,36. Varying the transmission frequency in the range f_(U) to f_(B), Δf,results in a variation in the transferred power transfer, V_(U) toV′_(B). Thus, any variations in the toggling frequency result inapproximate changes in the transferred power result. This is in contrastto variations in the transmission frequency at the resonant frequencywhich result in large variations in the transferred power.

Alternatively, if a transmission frequency range, such as f′_(U) tof′_(B), is selected, a variation 38 in power transfer at a lower voltageV′_(U) to V_(B) may be obtained. Accordingly, the inductive powertransfer system may transmit power at multiple power levels by adjustingthe transmission frequency range.

Reference is now made to FIG. 3 , which presents a typical circuitdiagram 38 of the inductive power transfer system 10, in accordance witha particular embodiment of the present disclosure. FIG. 3 shows that thedriver device 24 includes, inter alia, four electronic switches M1, M2,M3, and M4. Optionally, M1, M2 M3, and M4 are N-type MOFSET switches.The switches M1 and M2 are controlled by a microprocessor 50, such asLTC4442 High Speed Synchronous N-Channel MOFSET Driver, and the switchesM3 and M4 are controlled by a microprocessor 52, such as LTC4442 HighSpeed Synchronous N-Channel MOFSET Driver. FIG. 3 shows that the driverdevice 24 includes, inter alia, an LC circuit 54. The LC circuit 54includes, inter alia, the primary inductor (L1) 22 and aserially-connected capacitor (C2) 56. The primary inductor (L1) 22 isinductively coupled to the secondary inductor (L2) 30.

It is appreciated that the resonance frequency, f_(r), is determined bythe values of the components of the LC circuit 54 as well as therelative positioning of the primary inductor (L1) 22 and the secondaryinductor (L2) 30. Optionally, the toggling frequency, f_(T), is adjustedin incremental frequency steps, Δf, which may be selected from within apermissible range of approximately f_(U) to f_(B). A typical value of afrequency range f_(U) to f_(B) is 180 kHz to 380 kHz, respectively, inincremental frequency steps, Δf, 250 Hz.

FIG. 3 also shows that the secondary inductor 30 is conductively coupledto the electrical device 14 by an AC-DC rectifier 60. The rectifier 60rectifies the transferred AC power 12 to the electrical device 14, inaccordance with the electrical power requirements of the electricaldevice 14.

It is appreciated that the inclusion of the rectifier 60 in the powertransfer system 10 is optional. If the electrical device 14 is anAC-operating device, the AC-DC rectifier 60 is excluded from the powertransfer system 10.

It is further appreciated that the operation of the microprocessors 50and 52 may be coordinated, for example for synchronized toggling.

Reference is now made to FIG. 4 , which shows a power converter 62 ofthe driver device 24, in accordance with a selected embodiment of thepresent disclosure. FIG. 4 shows that the switching portion 62 includes,inter alia, the four electronic switches M1, M2, M3, and M4, which areconductively coupled to the DC power supply 18. The four switches M1,M2, M3, and M4 form a full-bridge (H-bridge) power inverter 64 forconverting the DC voltage 26 into the AC voltage 28, which isinductively transferred to the power receiver unit 20.

The full-bridge power converter 64 includes a first half-bridge powerconverter 66 and a second half-bridge power converter 68. The firsthalf-bridge converter 64 includes switches M1 and M2 and the secondhalf-bridge converter 68 includes switches M3 and M4. The LC circuit 54conductively links the first half-bridge converter 66 and the secondhalf-bridge converter 68.

The first half-bridge converter 66 includes, inter alia, the firstelectronic switch M1 which is operable to selectively conductivelycouple an anode 72 (FIG. 3 ) of the DC power supply 18 to a firstterminal 74 of the primary inductor 22. The second electronic switch M2is operable to selectively conductively couple a cathode 76 (FIG. 3 ) ofthe DC power supply to the first terminal 74 of the primary inductor.The third electronic switch M3 is operable to selectively conductivelycouple the anode 72 (FIG. 3 ) of the DC power supply 18 to a secondterminal 78 of the primary inductor 22. The fourth electronic switch M4is operable to selectively conductively couple the cathode 76 of the DCpower supply 18 to a second terminal of the primary inductor 22.

In order to generate the AC current 27 from the input DC current 26, thepower inverter 46 toggles between a first operational state of thedriver device 24 and a second operational state of the driver device 24.The toggling frequency, f_(T), is controlled by the microprocessors 50and 52.

In the first operational state, optionally, the first electronic switchM1 is operating in an ON-state, the second electronic switch M2 isoperating in an OFF-state, the third electronic switch M3 is operatingin an OFF-state, and the fourth electronic switch M4 is operating in anON-state. Thus, in the first operational state, the voltage at the firstterminal 74 is +V, volts, where V volts is the DC voltage generated atthe anode 72. Furthermore, the DC voltage at a first plate 80 of thecapacitor 56 is −V volts, and, therefore, the DC voltage at a secondplate 82 is +V volts. Thus, the voltage at the second terminal 78 is −Vvolts and the total AC voltage variation across the inductance 54 is +Vvolts.

In the second operational state, optionally, the first electronic switchM1 is operating in an OFF-state, the second electronic switch M2 isoperating in an ON-state, the third electronic switch M3 is operating inan ON-state, and the fourth electronic switch M4 is operating in anOFF-state. Thus, in the second operational state, the voltage at thefirst terminal 74 is −V, volts, the DC voltage at the first plate 80 ofthe capacitor 56 is +V volts, the DC voltage at the second plate 82 is−V volts, and the DC voltage at the second terminal 78 is +V volts andthe total AC voltage variation across the inductance 54 is −V volts.

Thus, the total AC voltage variation across the inductance 54 is .±0.2Vvolts, and an AC voltage of approximately ±V volts is inductivelytransferred to the power receiver device 20. The AC voltage transferredto the electrical device 14 by means of the communications links 15 and12 is therefore, approximately, ±V volts.

Therefore, by toggling the power inverter 64 between a first operationalstate and a second operational state, the AC voltage 28 of ±V volts istransferred to the electrical device 14 by means of the communicationslink 12.

It is appreciated that the variable DC power supply 18 generates the DCcurrent 26 at a plurality of electrical power levels as a function ofthe AC transmission frequency, f (FIG. 2 ).

It is particularly noted that the inductive power transmission systemmay operate at a second power level by fixing electronic switch M3 inthe OFF state and electronic switch M4 in the ON state and toggling onlybetween electronic switch M1 and electronic switch M2. Therefore,electronic switch M1 and electronic switch M2 are effectively configuredto operate as a half-bridge converter 66.

Reference is now made to FIG. 5 , which shows an equivalent electroniccircuit 90 of the switching portion 62 of the driver device 24,configured to operate at the second power level with electronic switchM3 fixed in the OFF state and electronic switch M4 fixed in the ONstate.

The half-bridge converter 66 includes, inter alia, the two electronicswitches M1 and M2 which are conductively coupled to the anode 72 of thevariable DC power supply 18 for converting the DC voltage 26 into the ACvoltage 27, which is inductively transferred to the power receiver unit20.

In the second power mode, in order to generate the AC current 27 fromthe input DC current 26, at the second power mode, the power inverter 46toggles between a first operational state of the driver device 24 and asecond operational state of the driver device 24. The togglingfrequency, f_(T), is controlled by the microprocessors 50 and 52.

In the first operational state, optionally, the first electronic switchM1 is operable in an ON-state, the second electronic switch M2 isoperable in an OFF-state, the third electronic switch M3 is operable inan OFF-state, and the fourth electronic switch M4 is operable in anON-state. In the second operational state, the first electronic switchM1 is operable in an OFF-state, the second electronic switch M2 isoperable in an ON-state, the third electronic switch M3 is operable inan OFF-state, and the fourth electronic switch M4 is operable in anON-state.

In the second power mode, as shown in the equivalent circuit of FIG. 5 ,since the switch M3 is operating in an OFF-state, M3 is notparticipating in the operation of the half-bridge 66 and is thusexcluded from FIG. 5 . Furthermore, since M4 is operating in anON-state, M4 is shown as a short circuit conductively coupled to ground.

In the first operational state of the second power mode, the firstelectronic switch M1 is operable in an ON-state, the second electronicswitch M2 is operable in an OFF-state, the third electronic switch M3 isoperable in an OFF-state, and the fourth electronic switch M4 isoperable in an ON-state. Thus, in the first operational state, thevoltage at the first terminal 74 is +V, volts, where V volts is the DCvoltage generated at the anode 72. The DC voltage at the first plate 80of the capacitor 56 is −V volts, and the DC voltage at the second plate82 is +V volts. The voltage at the second terminal 78 is +V volts, and,thus, the total AC voltage variation across the inductance 54 is +Vvolts.

In the second operational state of the second power mode, the firstelectronic switch M1 is operable in an OFF-state, the second electronicswitch M2 is operable in an ON-state, the third electronic switch M3 isoperable in an OFF-state, and the fourth electronic switch M4 isoperable in an ON-state. Thus, in the second operational state of thesecond power mode, the voltage at the first terminal 74 is −V volts, theDC voltage at the first plate 80 of the capacitor 56 is −V volts, andthe DC voltage at the second plate 82 is +V volts. The voltage at thesecond terminal 78 is +V volts, and, thus, the total AC voltagevariation across the inductance 54 is 0 V volts.

Thus, the total AC voltage variation across the inductance 54 is from 0volts to +V volts.

Therefore, by toggling the first half-bridge 66 between the firstoperational state and the second operational state, in the second powermode, an AC voltage varying from 0 volts to +V volts, is transferred tothe electrical device 14 by means of the communications links 15 and 12.

Accordingly, the second power mode (FIG. 5 ) produces a smaller voltagerange than the first power mode (FIG. 4 ).

It is appreciated that the power requirements of the electrical device14 are determined by the manufacturer.

Reference is now made to FIGS. 6A and 6B, which present typical driveroutput voltages of the driver device 24 operating in the first powermode (94) and the second power mode (96), respectively, in accordancewith a selected embodiment of the present disclosure.

The voltage output 94 generated by the full-bridge converter 64 (FIG.6A) is compared with a typical voltage variation 96 generated by thehalf-bridge 66 (FIG. 6B). FIG. 6A shows that the full-bridge converter64 optionally generates a full-square-wave AC voltage of range ±2Vvolts, and FIG. 6B shows that the half-wave converter 66 optionallygenerates a half-square-wave voltage of range 0 volts to +V volts.

The voltage outputs 94 and 96 are shown as square-wave functions. It isappreciated that voltage outputs 94 and 96 have finite-rise times andfinite-decay times.

Reference is now made to FIG. 7 , in which operational power variations100 for the first and second power modes are shown as a function of thetransmission frequency, f, in accordance with the selected embodiment ofthe present disclosure. FIG. 7 shows a power variation 102 for thefull-bridge converter 64 as a function of the transmission frequency, f,in a first power mode 104. FIG. 7 also shows a power variation 106 forthe first half-bridge converter 66 as a function of the transmissionfrequency in a second power mode 108. In FIG. 7 it can be deduced thatat the resonance frequency, f_(R), the maximum voltage for thefull-bridge converter 66 is approximately twice the maximum voltage ofthe half-bridge converter 64.

It is noted that the multipower inductive power transmission unit of theembodiment may allow power to be transmitted at multiple voltage rangesfor a given transmission frequency range. Accordingly, by way ofexample, using a given transmission frequency range, such as f_(U) tof_(B), in the first power mode, power may be transmitted having avoltage range of V_(U) to V_(B). Whereas, in the second power mode, atthe same frequency range f_(U) to f_(B) power may be transmitted at alower voltage range V_(1U) to V_(1B).

It will be appreciated that it is a particular advantage of such anarrangement that the driver may be optimized to work efficiently at asingle frequency range and yet to produce multiple power levels.

Thus, with the present embodiment, V_(U)=2V_(1U) and V_(B)=2V_(1B).Optionally, with the present embodiment, the power requirement of asecond electrical device such as a mobile communication device is lowerthan the power requirement of the first electrical device such as atablet computer for example.

Therefore, by operating the power converter 64 in power modes, differentelectrical devices are operable with the present disclosure.

Reference is now made to FIG. 8 , which shows variations of anoperational power 120 as a function of the transmission frequency, f,for another embodiment of the inductive power unit operable at furtherpower modes 122. By varying the DC current a range of operational powerlevels as a function of the AC transmission frequency are available.Accordingly, FIG. 8 shows that several power level modes 124, 126, 128,and 130 may be obtainable, for example, by varying the DC current 26.

Reference is now made to FIG. 9 , which presents further features of theinductive power transfer system 10, in accordance with anotherembodiment of the present disclosure. FIG. 9 shows that the inductivepower transfer system 10 also includes a power monitor 140 whichcontinually monitors the electrical power inductively transferredbetween the power outlet unit 16 and the electrical device 14. The powermonitor 140 is coupled to the secondary inductor 30 via a communicationslink 142. The monitoring of the inductively transferred electrical power12 by the monitor 140 ensures that the power transferred is theelectrical power required by the electrical device 14 and is within thepower requirements of the electrical device 14 as well as complying withsafety requirements of the power transfer system 10 and the electricaldevice 14.

The power monitor 140 is coupled to the secondary inductor 30 by acommunications link 142 and optionally, inductively monitors theelectrical power 12 inductively transferred to the electrical device 14by the inductive power transfer system 10. The power monitor 140 iscoupled to a feedback signal generator 144 by a communications link 141and forwards monitoring signals 143 to a feedback signal generator 144.In accordance with the monitoring signals 143, the feedback generator144 generates a feedback signal 146. The monitor 140 generates anappropriate feedback signal 146 in accordance with the results of themonitoring of the transferred electrical power 12, as described below.

The feedback signal generator 144 forwards the feedback signal 146 to atransmitter 147 which modulates the feedback signal 146 to comply withthe transmission requirements of a feedback communications channel 148.The transmitter 147 transmits a modulated signal 150 to a receiver 152,located within the power transfer outlet unit 16. The receiver 152demodulates and processes the received signal 150. If the transferredpower does not comply with the power requirements of the electricaldevice, the receiver 152 forwards an adjustment signal 154 to the driverdevice 24 by means of a communications link 156. On receiving the signal154, the driver device 24 adjusts the toggling frequency, f_(T), of thepower bridge 64, so that the transferred power 12 complies with thepower requirements of the electrical device 12 (FIG. 2 ).

The feedback communications channel 148 forwards a power transfer statusby communications means, such as a magnetic inductive communicationschannel, an acoustic communications channel, an electromagneticcommunications channel, such an RF communications channel, an IRcommunications channel and/or an optical communications channel, aBluetooth communications channel, a WiFi communications channel, and anycombination thereof.

It is appreciated that the transmitter 147 and the receiver 152 areselected in accordance with the requirements of the feedbackcommunications channel 148.

It is also appreciated that the communications channel 148 is anindependent communications channel and is remote from the electricalpower transfer channel 35.

If the power monitor 140 senses that the transferred electrical power 12is within a predetermined recommended power range of the electricaldevice 14, such as within the power range requirements recommended bythe manufacturer, the power monitor 140 does not generate a monitoringsignal 141 and the power transfer unit 10 maintains the current powerlevel transferred to the electrical device 14.

It is further appreciated that if the electrical device 14 requires a DCsupply, for example, a charging device for an electrochemical cell orthe like, an AC-DC rectifier 60 is provided in order to rectify theinduced AC current 34.

Referring back to FIG. 2 and in accordance with a selected embodiment ofthe current disclosure, the selected power transfer 12 between theinductive power transfer system 10 and the electrical device 14 isoptionally in the approximately linear region 36. In the linear region36 the power transfer range is from approximately from V_(U) to V_(B)with a corresponding frequency range of approximately f_(U) to f_(B),respectively. The voltage range V_(U) to V_(B) is within themanufacturer's recommendations.

If the monitor 40 senses that the transferred power 12 deviates from therecommended power requirements, the transferred power 12 is adjusted inorder to maintain the recommended power supply to the electrical device14.

If the monitor 140 senses that the transferred voltage 12 is out of therange V_(U) to V_(B), the monitor 140 forwards an appropriate monitoringsignal 143 to the feedback generator 144. If the sensed voltage isgreater than V_(U), the monitor forwards the monitoring signal 143 tothe feedback signal generator 144 for reducing the transferred power 12to remain within the manufacturer's requirements. The feedback signalgenerator 144 generates a power-reducing signal 160 and forwards thesignal 160 to the transmitter 147. The transmitter 147 modulates andtransmits the signal 160 to the receiver 152. The receiver 152demodulates and processes the signal 160 in order to generate theadjustment signal 154. The adjustment signal 154 is forwarded to thedriver device 24. The driver device 24 receives the adjustment signal154 and reduces the transferred power 12 by appropriately reducing thetoggling frequency f_(T).

If the monitor 140 senses that the transferred voltage 12 is out of thevoltage range V_(U) to V_(B), the monitor 140 forwards an appropriatemonitoring signal 143 to the feedback generator 144. If the sensedvoltage is less than V_(B), the monitor forwards the monitoring signal143 to the feedback signal generator 144 for increasing the transferredpower 12 to remain within the manufacturer's requirements. The feedbacksignal generator 144 generates a power-increasing signal 162 which isforwarded to the transmitter 147. The transmitter modulates andtransmits the signal 162 to the receiver 152. The receiver 152demodulates and processes the signal 162 and generates the adjustmentsignal 154. The adjustment signal 154 is forwarded to the driver device24. The driver device 24 receives the adjustment signal 154 andincreases the transferred power 12 by appropriately increasing thetoggling frequency f_(T).

Additionally, the power transfer system 10 includes, inter alia, asafety monitoring device 170 which continually monitors the operation ofthe power transfer supply system 10. If the monitor 170 senses that theelectrical and/or temperature safety features of the system 10 areexceeded, the monitor device 170 ceases the operation of the powertransfer supply system 10 by forwarding a stop-functioning signal 172 tothe DC power supply 18 as well as forwarding an appropriate visual/audiowarning signal 174 to a visual/acoustic display unit 176, via acommunications link 178.

Reference is now made to FIG. 10 , which presents a flow chart 500 for amethod for inductively transferring the electrical power 12 to theelectrical device 14.

In step 502, providing at least one inductive power outlet unit 16including at least one primary inductor 22.

In step 504, conductively associating a driver device 24 with thevariable DC power supply 18.

In step 506, providing a power inverter 64 for converting the DC voltage26 to the AC voltage 28.

In step 508, configuring the driver device 24 to toggle between thetoggling frequencies in order to provide the AC voltage 28 across the atleast one primary inductor 22.

In step 510, configuring the power receiver unit 30 to inductivelyreceive the AC voltage 28 and forward the electrical power 12 to theelectrical device 14.

In step 512, generating a feedback signal in order to adjust thetoggling frequency of the driver device 24 so that transferredelectrical power is within the power requirements of the electricaldevice 14.

In the foregoing description, embodiments of the disclosure, includingselected embodiments, have been presented for the purpose ofillustration and description. They are not intended to be exhaustive orto limit the disclosure to the precise form disclosed. Obviousmodifications or variations are possible in light of the aboveteachings. The embodiments were chosen and described to provide the bestillustration of the principals of the disclosure and its practicalapplication, and to enable one of ordinary skill in the art to utilizethe disclosure in various embodiments and with various modifications asare suited to the particular use contemplated. All such modificationsand variations are within the scope of the disclosure as determined bythe appended claims when interpreted in accordance with the breadth theyare fairly, legally, and equitably entitled.

Aspects of the present disclosure further relate to an inductive powertransfer system including a multi-mode inductive power receiver. Themulti-mode inductive power receiver is operable in a plurality ofdifferent modes to use more than one control protocol such that it maybe compatible with a variety of different inductive power outlets.

The multi-mode inductive power receiver may include a secondary inductoroperable to inductively couple with a primary inductor associated withthe inductive power outlet. Optionally, the secondary inductor may beconfigured to operate selectively with a plurality of inductance valuesas required. A mode selector may select the operating mode according toproperties of the inductive power outlet, for example, initialtransmission frequency or the like.

It is noted that the systems and methods of the disclosure herein maynot be limited in its application to the details of construction and thearrangement of the components or methods set forth in the description orillustrated in the drawings and examples. The systems and methods of thedisclosure may be capable of other embodiments or of being practiced orcarried out in various ways. It is also noted that the multi-modeinductive power receiver may be incorporated into the inductive powertransfer system of the disclosure as described in reference to FIGS.1-10 (e.g., as the inductive power receiver unit 20 of FIG. 1 ).

Alternative methods and materials similar or equivalent to thosedescribed herein may be used in the practice or testing of embodimentsof the disclosure. Nevertheless, particular methods and materials aredescribed herein for illustrative purposes only. The materials, methods,and examples are not intended to be necessarily limiting.

Reference is made to the block diagram of FIG. 11 , showing selectedelements of an inductive power transfer system 101 including amulti-mode inductive power receiver 300 operable to receive power froman inductive power outlet 200.

The inductive power outlet 200 comprises a primary inductor 220 wired toa power source 240 via a driver 230. The driver 230 is operable togenerate a voltage oscillating at a transmission frequency across theprimary inductor 220. Accordingly, the driver may include variouselements such as inverters, choppers, or the like such as described inthe applicant's co-pending U.S. patent application Ser. No. 13/205,672,now U.S. Pat. No. 8,981,598.

The inductive power receiver 300 includes a secondary inductor 320 wiredto an electric load 340 via a reception circuit 330. When in proximitywith the primary inductor 220, the secondary inductor 320 is operable toinductively couple therewith. Accordingly, an AC voltage oscillating atthe transmission frequency is induced in the secondary inductor.

The inductive power transfer system 101 may further include a signaltransfer mechanism (not shown) for transferring feedback signals fromthe receiver 300 to the outlet 200 for the purposes of power regulation,identification, or the like. A variety of operating protocols arecurrently used for controlling power transfer, for example, in onepossible protocol operates with a transmission voltage of 10 volts andwith a transmission frequency varying between 110 kilohertz and 205kilohertz. In another protocol with a higher transmission voltage ofabout 30 volts, the transmission frequency may vary between say about277 kilohertz and 357 kilohertz, or between 232 kilohertz and 278kilohertz. Another protocol is described in the applicant's co-pendingU.S. patent application Ser. No. 13/205,672, now U.S. Pat. No.8,981,598. Still, other protocols may be used.

It is particularly noted that the multi-mode inductive power receiver300 is configured to be compatible with a plurality of protocols suchthat it may be compatible with a variety of inductive power outlets 200.Accordingly, the reception circuit 330 may include a mode selector 334for selecting the required mode according to preferred protocol of theinductive power outlet 200 coupled thereto.

Where operating modes are characterized by operating frequency of theprimary inductor 220, the reception circuit 330 may further include afrequency detector 332 for detecting the initial transmission frequencyof the primary inductor 220. The mode selector 334 may be incommunication with such a frequency detector 334 and operable to selectoperating mode according to the transmission frequency. For example, ifan initial transmission frequency is below a threshold of, for example,250 kilohertz, the protocol operating between 110-205 kilohertz may beselected, whereas if an initial transmission frequency is above thethreshold, the protocol operating between 277-357 kilohertz may beselected. Similarly, if an initial transmission frequency is below athreshold of, for example, 210 kilohertz, the protocol operating between110-205 kilohertz may be selected, whereas if an initial transmissionfrequency is above the threshold, the protocol operating between 232-278may be selected. Furthermore, where required, the initial transmissionfrequency may be set to a characteristic level, possibly outside thegeneral operating range, for the purposes of such selection.

Optionally, the secondary inductor 320 may be a dual mode secondaryinductor configured to operate selectively with more than one inductancevalue as required. The mode selector may be operable to select theinductance value appropriate for a particular protocol. In particular, alower impedance may be required for the protocol operating at 30 voltsbetween 277-357 kilohertz, whereas a higher impedance may be requiredfor the protocol operating at 10 volts between 110-205 kilohertz.

Referring now to FIGS. 12A and 12B, a schematic representation of aparticular example of a multi-inductance secondary inductor 2200 isshown. The multi-inductance secondary inductor 2200 is configured tooperate selectively with more than one inductance value.

The secondary inductor 2200 of the example comprises a coil 2202 ofconducting material, such as copper metal for example, having threeterminals 2210, 2212, 2214. The terminals may be connected to aninductive receiver circuit 330 (FIG. 11 ) selectively, so as to providevarious inductance values as required.

The coil 2202 comprises a spiraled wire of conducting material 2202having an inner end 2204 and an outer end 2206. The inner end 2204 ofthe spiraled wire is connected to an inner terminal 2210. The outer end2206 of the spiraled wire is connected to an outer terminal 2214. It isa particular feature of the disclosure that a third intermediateterminal 2212 is connected to the spiraled point at some intermediatepoint 2208 between the inner end 2204 and the outer end 2206. Optionallythe coil may comprise an inner spiral and an outer spiral with the innerend of the outer spiral juxtaposed against the outer end of the innerspiral and the intermediate terminal being connected to the juxtaposedwires such as shown in FIG. 12B.

Accordingly, the inductance of the coil 2200 between the inner terminaland the outer terminal is higher than the inductance of the coil 2200between the intermediate terminal and the outer terminal Thus, theinductance of the coil may be adjusted by selecting which pair ofterminals are connected the reception circuit.

In one particular example a copper coil may have a total of 14 windingsbetween the inner terminal and the outer terminal. The inner diametermay be about 20 millimeters and the outer diameter may be about 33millimeters. The intermediate terminal may be connected to a point 2208such that there are eight windings between the intermediate terminal andthe outer terminal. Accordingly, the inductance at 100 kilohertz and 1volt between the inner terminal and the outer terminal is about 7.5microhenries, and the inductance between the intermediate terminal andthe outer terminal is about 3.2 microhenries. For the same coil thedirect current resistance between the inner terminal and the outerterminal is about 298 micro-ohms, and the direct current resistancebetween the intermediate terminal and the outer terminal is about 188micro-ohms.

Referring now to FIG. 13 another block diagram shows selected elementsof a particular multi-mode secondary receiver 2000 incorporating amulti-inductance secondary inductor 2200 such as described hereinabove.

The multi-mode secondary receiver 2000 includes the multi-inductancesecondary inductor 2200, a first resonant tuning circuit 2102, a secondresonant tuning circuit 2104, an AC switch 2106, a dual mode receiver2108, and a load 2110.

The multi-inductance secondary inductor 2200 includes three terminals.The outer terminal 2214 serves as a common terminal wired to the dualmode receiver 2108. The intermediate terminal 2212 serves as a firstmode terminal, and the inner terminal 2210 serves as a second modeterminal.

The AC switch 2106 is operable to select the desired mode by selectivelyconnect the dual mode receiver 2108 to the intermediate terminal 2212via the first resonant tuning circuit 2102 or to the inner terminal 2210via the second resonant tuning circuit 2104. Accordingly, the dual modereceiver 2108 may be connected to a first pair of terminals with a firstinductance or a second pair of terminals with a second inductance.

The dual mode receiver 2108 includes a controller 2112, a rectifier2114, and a voltage control circuit 2116. Accordingly, the dual modereceiver is operable to regulate the power transfer using whicheverprotocol is appropriate for the coupled inductive power outlet.

Referring now to electrical schematics of FIGS. 14A-G, various sectionsof a particular multi-mode inductive reception circuit are presented forillustrative purposes only. In particular, FIG. 14A represents a commonterminal 402, a first mode terminal 404, and a second mode terminal 406.The first terminal 404 is connected to a first resonant tuning circuit408 and a charge pump 412. The second mode terminal 406 is connected tothe second resonant tuning circuit 410

FIG. 14B represents the controller 414 of the reception circuit, andsuch a controller may be an integrated circuit configured to select anoperational mode and to perform power regulation accordingly. It isparticularly noted that the chip may include a frequency detectoroperable to output a signal WPC from pin number 7. The WPC signal may beused to select the mode via the AC switches of FIGS. 14D and 14E.

FIG. 14C represents a signal inverter configured to invert the WPCsignal producing a zero nWPC signal if the WPC signal is in its ONstate.

FIGS. 14D and 14E represent AC switches for the first mode and secondmode, respectively.

The first mode AC switch of FIG. 14D includes a pair of N-channel FETsQ1 having a common source signal, and a pair of P-channel FETs U3 havinga common gate signal. The pair of N-channel FETs are triggered by theWPC signal. The P-channel FETs and configured to connect the receptioncircuit controller AC IN to the first mode terminal AC PM of thesecondary inductor. The common gate signal of the P-channel FETs isdrawn from a charge pump via the pair of N-channel FETs.

The second mode AC switch of FIG. 14E includes a pair of N-channel FETsQ2 having a common source signal, and a pair of P-channel FETs U2 havinga common gate signal. The pair ofN-channel FETs are triggered by thenWPC signal. The P-channel FETs and configured to connect the receptioncircuit controller AC IN to the second mode terminal AC WPC of thesecondary inductor. The common gate signal of the P-channel FETs isdrawn from a charge pump via the pair of N-channel FETs.

It is noted that alternative AC switches may be used, for example, usingcomplementary P-channel and N-channel FETs.

FIG. 14F shows a possible pair of rectifying MOSFETS which may be usedin combination with rectifiers in the controller to rectify the ACcurrent, for example, as described in the applicant's co-pending U.S.patent application Ser. No. 12/423,530, now U.S. Pat. No. 8,320,143, forexample.

FIG. 14G shows a possible signal buffer for the feedback communicationsignal COM sent from the receiver to the outlet.

Referring now to the flowchart of FIG. 15 various actions are presentedof a method for selecting operational mode of a multi-mode inductivepower receiver. A voltage is induced in the secondary coil 2502, theoperating frequency is detected 2504. The frequency is compared to athreshold value, such as 250 kilohertz, 210 kilohertz or the like 2506.If the operating frequency is above the threshold, a first operatingmode is selected 2508 and the first mode terminal is connected to thereception circuit 2510. If the operating frequency is below thethreshold, a second operating mode 2512 is selected, and the second modeterminal is connected to the reception circuit 2514. Other methods maybe used.

Technical and scientific terms used herein should have the same meaningas commonly understood by one of ordinary skill in the art to which thedisclosure pertains. Nevertheless, it is expected that during the lifeof a patent maturing from this application many relevant systems andmethods will be developed. Accordingly, the scope of the terms such ascomputing unit, network, display, memory, server, and the like areintended to include all such new technologies a priori.

As used herein the term “about” refers to at least ±10%.

The terms “comprises”, “comprising”, “includes”, “including”, “having”,and their conjugates mean “including but not limited to” and indicatethat the components listed are included, but not generally to theexclusion of other components. Such terms encompass the terms“consisting of” and “consisting essentially of.”

The phrase “consisting essentially of” means that the composition ormethod may include additional ingredients and/or steps, but only if theadditional ingredients and/or steps do not materially alter the basicand novel characteristics of the claimed composition or method.

As used herein, the singular form “a”, “an”, and “the” may includeplural references unless the context clearly dictates otherwise. Forexample, the term “a compound” or “at least one compound” may include aplurality of compounds, including mixtures thereof

The word “exemplary” is used herein to mean “serving as an example,instance or illustration”. Any embodiment described as “exemplary” isnot necessarily to be construed as preferred or advantageous over otherembodiments or to exclude the incorporation of features from otherembodiments.

The word “optionally” is used herein to mean “is provided in someembodiments and not provided in other embodiments”. Any particularembodiment of the disclosure may include a plurality of “optional”features unless such features conflict.

Whenever a numerical range is indicated herein, it is meant to includeany cited numeral (fractional or integral) within the indicated range.The phrases “ranging/ranges between” a first indicate number and asecond indicate number and “ranging/ranges from” a first indicate number“to” a second indicate number are used herein interchangeably and aremeant to include the first and second indicated numbers and all thefractional and integral numerals therebetween. It should be understood,therefore, that the description in range format is merely forconvenience and brevity and should not be construed as an inflexiblelimitation on the scope of the disclosure. Accordingly, the descriptionof a range should be considered to have specifically disclosed all thepossible subranges as well as individual numerical values within thatrange. For example, description of a range such as from 1 to 6 should beconsidered to have specifically disclosed subranges such as from 1 to 3,from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., aswell as individual numbers within that range, for example, 1, 2, 3, 4,5, and 6 as well as non-integral intermediate values. This appliesregardless of the breadth of the range.

It is appreciated that certain features of the disclosure, which are,for clarity, described in the context of separate embodiments, may alsobe provided in combination in a single embodiment. Conversely, variousfeatures of the disclosure, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination or as suitable in any other describedembodiment of the disclosure. Certain features described in the contextof various embodiments are not to be considered essential features ofthose embodiments, unless the embodiment is inoperative without thoseelements.

Although the disclosure has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims.

All publications, patents and patent applications mentioned in thisspecification are herein incorporated in their entirety by referenceinto the specification, to the same extent as if each individualpublication, patent or patent application was specifically andindividually indicated to be incorporated herein by reference. Inaddition, citation or identification of any reference in thisapplication shall not be construed as an admission that such referenceis available as prior art to the present disclosure. To the extent thatsection headings are used, they should not be construed as necessarilylimiting.

The scope of the disclosed subject matter is defined by the appendedclaims and includes both combinations and sub combinations of thevarious features described hereinabove as well as variations andmodifications thereof, which would occur to persons skilled in the artupon reading the foregoing description.

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention that may be embodied in variousand alternative forms. The figures are not necessarily to scale; somefeatures may be exaggerated or minimized to show details of particularcomponents. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as arepresentative basis for teaching one skilled in the art to variouslyemploy the present invention.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms of the invention. Rather,the words used in the specification are words of description rather thanlimitation, and it is understood that various changes may be madewithout departing from the spirit and scope of the invention.Additionally, the features of various implementing embodiments may becombined to form further embodiments of the invention.

What is claimed:
 1. An inductive power outlet for inductively powering areceiver, the inductive power outlet cornprising: at least one inductorinductively coupled to a coil of the receiver having together a resonantfrequency; and a driver comprising at least one switch, the driver beingconfigured to: generate power in accordance with the at least one switchby converting a DC voltage supplied by a power supply to an AC voltage,a frequency of the AC voltage being different from the resonantfrequency, and vary the frequency of the AC voltage to apply the ACvoltage within a range of AC voltages across the at least one inductor.2. The inductive power outlet of claim 1, wherein the driver isconfigured to regulate energy transmitted by the at least one inductorby adjusting a duty cycle of the AC voltage.
 3. The inductive poweroutlet of claim 1, wherein the frequency of the AC voltage is eitherlower or higher than the resonant frequency.
 4. The inductive poweroutlet of claim 1, wherein the at least one switch comprises at leasttwo switches configured to collectively operate as a half-bridgerectifier to apply the AC voltage across the at least one inductor. 5.The inductive power outlet of claim 1, wherein the at least one switchcomprises at least four switches configured to collectively operate as afull-bridge rectifier to apply the AC voltage across the at least oneinductor.
 6. The inductive power outlet of claim 5, wherein two of thefour switches are set in a fixed off state while the remaining two ofthe four switches are set in an on to collectively operate as ahalf-bridge rectifier to apply the AC voltage across the at least oneinductor.
 7. The inductive power outlet of claim 1, wherein theinductive power outlet comprises a signal receiver configured todemodulate, and process a feedback signal received from the receiver. 8.The inductive power outlet of claim 7, wherein if a transferred powerdoes not comply with power requirements of an electrical device, thesignal receiver forwards an adjustment signal to the driver.
 9. Theinductive power outlet of claim 8, wherein the driver adjusts thefrequency of the AC voltage in accordance with the adjustment signal.10. The inductive power outlet of claim 1, wherein the inductive poweroutlet is configured to regulate the energy transmitted by the at leastone inductor according to power requirements of the receiver.
 11. Theinductive power outlet of claim 1, wherein the driver is configured toselect one of a plurality of power levels.
 12. The inductive poweroutlet of claim 1, wherein the driver is configured to selectivelyactivate a first switch combination of the at least one switch inaccordance with a first power mode of the plurality of power levels.